Koro-zen: Forbidden color. It is longtime (1200 years) secret dyeing method, used only Emperor's formal jacket (Ho), recently rediscovered and upgraded by dyer Okuda Yusai in Kyoto (originally only kin-cha, yellowish brown, he made another colors.) There are two special effects with it: 1. The color will change by different lights, 2. Red circle (sun) will appear when light come from back.